added di docs

Signed-off-by: arhimede <julian@dotkernel.com>

Author: claurospace

docs/book/v5/core-features/dependency-injection.md

@@ -0,0 +1,59 @@
+# Dependency Injection
+
+Dependency Injection is a design pattern used in software development to implement inversion of control or in simple
+terms is the act of providing dependencies for an object during instantiation.
+
+In PHP, dependency injection can be implemented in various ways, including through constructor injection,
+setter injection, and property injection. 
+
+DotKernel API, through it's
+[dot-dependency-injection](https://github.com/dotkernel/dot-dependency-injection) package focuses only on constructor
+injection.
+
+## Usage
+DotKernel API comes out of the box with [dot-dependency-injection](https://github.com/dotkernel/dot-dependency-injection)
+package, which provide all we need for injecting dependencies in any object you want.
+
+`dot-dependency-injection` determines the dependencies by looking at the `#[Inject]` attribute,
+added to the constructor of a class. Dependencies are specified as separate parameters of the `#[Inject]`
+attribute.
+
+For our example we will inject a `UserService` and `config` dependencies in a `UseHandler`.
+
+```php
+use Dot\DependencyInjection\Attribute\Inject;
+
+class UserHandler implements RequestHandlerInterface
+{
+    #[Inject(
+        UserService::class,
+        "config",
+    )]
+    public function __construct(
+        protected UserServiceInterface $userService,
+        protected array $config,
+    ) {
+    }
+}
+```
+
+>If your class needs the value of a specific configuration key, you can specify the path using dot notation: `config.example`
+
+After register the class in the `ConfigProvider`, under `factories`, using `Dot\DependencyInjection\Factory\AttributedServiceFactory::class`
+
+```php
+public function getDependencies(): array
+{
+    return [
+        'factories' => [
+            UserHandler::class => AttributedServiceFactory::class
+        ]
+    ];
+}
+```
+
+That's it, by registering this, when your object will instantiate from the container, it will automatically resolve
+the dependencies needed for you object.
+
+>Dependencies injection applies to any object within DotKernel API, for example, you could inject dependencies in
+> a service and so on, just need to register it in the `ConfigProvider`

mkdocs.yml

@@ -31,6 +31,7 @@ nav:
           - "Content Validation": v5/core-features/content-validation.md
           - "Exceptions": v5/core-features/exceptions.md
           - "CORS": v5/core-features/cors.md
+          - "Dependency Injection": v5/core-features/dependency-injection.md
       - Commands:
           - "Create admin account": v5/commands/create-admin-account.md
           - "Generate database migrations": v5/commands/generate-database-migrations.md